Chapter 1 Vocabulary Words

Front 1

Point

Back 1

A location; has no shape or size

Front 2

Line

Back 2

A set of points that extend indefinitely in two directions; has length but no thickness or width

Front 3

Plane

Back 3

A flat surface made up of points that extends indefinitely in all directions; has length and width but no depth

Front 4

Collinear

Back 4

A name given to points on the same line

Front 5

Coplanar

Back 5

A name given to points on the same plane

Front 6

Space

Back 6

A boundless, three-dimensional set of all points

Front 7

Congruent

Back 7

Figures that have equal measures; figures that are the same shape and size;

Front 8

Segment

Back 8

A part of a line which consists of two endpoints and all the points between them

Front 9

DE

Back 9

the measure or length of \overline{DE}; the distance between points D and E

Front 10

Between

Back 10

B is between A and C if points A, B, and C are collinear and AB + BC = AC:

Front 11

Segment Addition Postulate

Back 11

If B is between A and C, then AB + BC = AC (the second part of the definition of between)

Front 12

Polygon

Back 12

A closed figure made up of segments

Front 13

Irregular figure

Back 13

A figure that cannot be classified as a single polygon

Front 14

Regular polygon

Back 14

A polygon that has congruent angles and congruent sides

Front 15

Perimeter

Back 15

The distance around a polygon; the sum of the sides

Front 16

Area

Back 16

The number of 1 by 1 unit squares that cover a 2-dimensional figure

Front 17

Midpoint

Back 17

A point halfway between the endpoints of a segment; K is the midpoint of J and L if K is between J and L and JK = KL

Front 18

Segment bisector

Back 18

A segment, line, ray, or plane that intersects a segment at its midpoint

Front 19

Ray

Back 19

A part of a line that has one endpoint and extends indefinitely in one direction

Front 20

Opposite rays

Back 20

Rays that have a common endpoint and extend in opposite directions

Front 21

Angle

Back 21

A figure formed by two rays, segments, or lines (sides) that share an endpoint (vertex)

Front 22

Degree

Back 22

A unit of measurement for angles; °

Front 23

m<R (m angle R)

Back 23

the measure of <R (angle R)

Front 24

Angle Addition Postulate

Back 24

If E is on the interior of <ABC, then m<ABE+m<EBC=m<ABC

Front 25

Acute angle

Back 25

An angle measuring greater than 0° and less than 90°

Front 26

Right angle

Back 26

An angle measuring 90°

Front 27

Obtuse angle

Back 27

An angle measuring greater than 90° and less than 180°

Front 28

Straight angle

Back 28

An angle measuring 180°

Front 29

Angle bisector

Back 29

A segment, line, or ray that divides an angle into two congruent angles

Front 30

Complementary angles

Back 30

A pair of angles whose sum is 90

Front 31

Supplementary angles

Back 31

A pair of angles whose sum is 180

Front 32

Adjacent angles

Back 32

a pair of angles that share a vertex and a side but do not share interior points

Front 33

Vertical angles

Back 33

A pair of nonadjacent angles formed by two intersecting lines

Front 34

Linear pair

Back 34

A pair of adjacent angles whose noncommon sides form opposite rays

Front 35

Perpendicular

Back 35

A name given to lines, segments, or rays that intersect to form a right angle;

Front 36

Four right angles

Back 36

Perpendicular lines form ... .

Front 37

Congruent

Back 37

Vertical angle’s are ... .

Front 38

Supplementary

Back 38

If two angles form a linear pair, then they are ... .

Front 39

Complementary

Back 39

If two angles form a right angle, then they are ... .